I wanted to authenticate myself as an other user with a keytab on Windows, but the requests-kerberos package cannot use the krb5 credential cache (and it's using SSPI, not GSSAPI) so it wasn't possible. The requests-gssapi package solved my problem (I have just replaced the requests-kerberos package with the mentioned one in the kerberos.py file)
I don't know if it would have any drawbacks (I'm not understanding 100% the Kerberos protocol), but from the description on the requests-gssapi repository, it should work out of the box.
Is it possible to switch to this package?